Eraser cleaning machine



March 28, 1939. c. L. GILBERT ERASER CLEANING MACHINE Filed Nov. 29,1957 INVENTOR A C/kzrZeJI G'zlezrt BY M ATTORNEY Patented Mar. 28, 1939UNITED STATES sA'rsur OFFICE ERASER CLEANING MACIHNE Charles L. Gilbert,Spokane, Wash.

Application November 29, 1937, Serial No. 177,050

'1 Claim.

The object of this invention is to provide a novel mechanism forcleaning black board erasers.

It is well known that these erasers are made of 5 porous felt whichbecomes permeated with chalk dust, and in the most improved erasers madeup of abutting strips of felt, the chalk dust gathers between thestrips, and in either case, the continued use of a chalk saturatederaser scatters and objectionable manner.

It is a feature of this invention to subject the erasers to sustainedagitation with the erasers bouncing against each other and impacting 5against unyielding surfaces in an indiscriminate manner so that allportions thereof will be subjected to a dust releasing action.

It is also a feature of the invention to subject the erasers to acurrent of air, preferably generated by suction, so that any dust thathas been released by agitation, will not be permitted to again enter theerasers but will be carried away therefrom. I

It is also an object of the invention to subject the erasers, as a body,or in the aggregate, to a rotary motion in such a manner thatcentrifugal force will not be effective to prevent the erasers fromfalling and bouncing under substantial normal gravity action due totheir weight.

It is also an object of that phase of the invention 'in which theerasers are subjected to a revolving motion, to admit air radiallyoutwardly from the axis of rotation and apply suction substantiallycoincident with and longitudinally along the axis of rotation.

The invention has many other objects and features which will be morefully described in connection with the accompanying drawing and whichwill be more particularly pointed out in and by the appended claim.

In the drawing:

Fig. 1 is a horizontal sectional view of one form of my improvedmechanism with parts thereof in elevation.

Fig. 2 is a sectional view on line 22 of Fig. 1, looking toward the leftof that figure.

Fig. 3 is a sectional view on line 3-3 of Fig. 1, looking toward theright. Fig. 4 is a plan view of a modern form of felt eraser looking atthe black board contacting surface thereof.

Fig. 5 is a sectional view thereof on an enlarged scale taken on line 55of Fig. 4.

Like characters of reference designate similar the dust in theatmosphere in a very unhealthy.

parts throughout the different figures of the drawing.

In the form shown, my improved agitator is in the form of a drum havinga cylindrical portion l, and a conical portion 2, formed of any suitablematerial such as sheet iron, for instance. The drum has a head 3,suitably secured thereto as at 4. A stub shaft is indicated at 5 and thesame is secured to head 3 by having its flange 6 riveted thereto. Apedestal bearing comprising a pedestal l and bearing 8, serves tojournal shaft 5, and form a rotatable support for one end of the drum, Asuitable base 9, forms a convenient support for the machine, and thepedestal l is shown secured thereto at In.

A bearing ll, having a pedestal l2, secured at l3, to base 9, forms theremaining rotary support for said drum. A suction shaft l4, which istubular to form a dust passage I5, is journalled in bearing l I andextends through the same toward the fan suction means, to be laterdescribed. A suitable fitting is provided having a cylindrical sectionI6, secured to the exterior of shaft I l and provided with a conicalsection I], secured to the conical portion of said drum, as shown, andthereby serves to close that end of the drum. The intake end l8, ofshaft M, extends a short distance into the coned end of said drum toform a support for one end of an eraser abutment or impact member whichadditionally functions as a dust egress means.

It will now be clear that shaft M is secured to the drum in a manner toform a rotative support therefor as well as to close the coned endthereof, and that the drum is effectively journalled in bearings 3 and Hfor rotative movement.

Reference will next be made to the dust egress member and to the mannerin which it is mounted.

As shown, said dust egress member is in the form of a hollow screen l9,which is cylindrical in cross section although this particular crosssection is not essential, and this member might be made of any type offoraminous material. I employ a screen of sufficient guage of wire to beself stable and in practice, the screen successfully used has a mesh ofone half inch openings. One end of the screen is shown mounted on theintake end of pipe l 4 by being telescoped over it and clamped by a ring26. The remaining end is socketed in a flange 29 formed integral with adisc 22, the latter being secured to head 3. Thus it will be seen thatthis impact member I9 is not only axially disposed in the drum but thatit also rotates with the drum, this latter being also an importantfeature.

The head 3, is provided with one or more air ingress openings 23 whichare disposed radially outwardly from the axially disposed air egress.Inside the drum is a plurality of eraser lifters which may comprisestrips of angle iron each having one flange 24, projecting radiallyinwardly of the drum and the remaining flange 25, secured to the drum,as shown. These lifters successively lift and then release the erasers,as will be subsequently described. An opening 26, in the drum is shownclosed by a lid 21 that ishinged at 28, and provided with a screw clamp29, at its free end whereby the drum may be opened to insert andwithdraw the erasers. On the periphery of the drum I have shown a pulley36 about which a belt 3| may be trained, the belt being driven by anysuitable source of power, not shown, to rotate the drum.

Reference will next be made to the manner and means for initiating acurrent of air through the agitating drum. 7 a

A suction fan is provided having a fan casing, the periphery of which isindicated at 32 and the sides at 33 and 3 3. The egress end 35, of pipel4, opens to the suction side of the fan casing through side wall 33,and to insure a dust proof engagements, sleeve 35 surrounds pipe i lbetween bearing H and the side wall 33 and is suitably flanged foreffective engagement with said parts and may be secured to side wall 33,as shown. Brackets 31 and 38, secured to walls 33 and 34, and to base 9,serve to support the fan casing, and a bearing 39 forms a part ofbracket 38 to journal a. fan shaft 40, which extends through wall 3 5and carries a fan M, having a hub 42, mounted on fan shaft 40. As asource of power, an electric motor. 43, mounted on a pedestal 45,secured to base 9, may be directly connected to the fan shaft &0. Thefan casing has a discharge outlet pipe 55 to which may be attached at46, any suitable kind of porous bag 5?, for collecting the dust andreleasing the air, the bag A! being inflated when the machine is inoperation, as indicated in Fig. 1.

The coned end 2, of the drum I, affords an additional drum area withoutunduly enlarging the cylindrical portion thereof, which has theadvantage of increasing the air volume for carrying off the chalk dust.This is due to the fact that the cone is at the discharge end of thedrum. Further, the cone is really an extension of the drum, as far asinterior area is'concerned, and I am thus able to locate the outletopening 58 endwise away from the cylindrical portion of the drum therebypermitting use of a longer abutment tube I9, which serves to increasethe air egressing capacity thereof. It will also be clear that the wallof the cone serves to converge the air currents toward the outlet 58,and prevents the formation of objectionable air eddies.

In Figs. 4 and 5, I have shown a modern eraser having a felt back 49,and a series of laterally abutting strips of felt 56, which are usuallyglued to the felt back 49, but are free from engagement with each other.As the eraser is used on a black board, the strips 56 separate from eachother to an extent sufficient to admit chalk dust between them, and thusit will be seen that it is not only the dust with which the felt becomespermeated or saturated, that is of importance, but also the dust betweenthe strips 58 that must be removed. It is also important to note thatthe felt from which these erasers are made, is sufiiciently porous toadmit of saturation of chalk dust.

The operation of my improved method and machine may be clear from theforegoing but I will briefly recapitulate the same as follows:

The lid 2? is opened and the drum is charged with erasers, and in mypresent machine, I can clean three hundred and fifty erasers in oneoperation. The drum is proportioned for a relatively large capacity toavoid frequent cleaning operations and I obtain the best results whenthere is a very marked congestion of erasers in the drum but not enoughto prevent the erasers from individually descending separately afterthey have been released, by the lifters.

After the drum has been charged, the lid is closed and power is appliedto belt 3| to rotate the drum. In practice, I have found that a speed ofabout forty revolutions per minute is an effective speed, and this rateof speed is important to a successful operation because centrifugalforce does not and should not function since if it did, these lightweight erasers would be impelled to cling to the inner face of the drum.Therefore a speed of rotation wherein centrifugal force is noteffective, is a primary requisite. This applies, not only to the erasersbut alsoto effective egress of the dust ladened air since the latter isegressed axially of the drum and hence centrifugal action would ratherretard than promote such discharge.

As the drum revolves, the lifters 2 3 successively pick up and elevatethe erasers and then drop or release them and they not only fall againsteach other but also against the screen, and when they impact against thescreen l9, their course is deflected and changed because said screenrotates with the drum.

I have successfully generated suction with the fan revolving at onethousand seven hundred and fifty revolutions per minute and it will beseen that the fan will draw air in through the radially outer ingressopenings 23, in head 3, and thereforethese streams of incoming air willmingle with the tumbling erasers that are descending, and also those inany peripheral relation to the impact member l9, and an importantfeature is that because the openings 23 revolve with the drum, thereis amost effective changing relation of the air intake as well as aconstantly changing position of the erasers. It will also be clear thatthese tumbling erasers will continually obstruct and divert currents ofdust ladened air and cause them to take circuitous paths of travel.

The dust ladened air is drawn through the screen impact member 59 at anylongitudinal pointin the drum as the screen provides an elongated egressair passage whose interior is unobstructed by the tumbling and bouncingerasers, and this is its value in addition to acting as an impactmember. It may also be stated that the screen l9, performs no functionas a screen, as there is nothing to separate, since all the dust ladenedair passes out through pipe M. However, I have found in practice, thatby extending the screen as shown, I greatly hasten the cleaningoperation.

The coned end of the drum, and the holes E3, prevent dust laden airaccumulations and also cause disruption of any air eddies. The dustladened air passes out through pipe hi and is admitted centrally of thefan casing from which it is peripherally discharged at 45, into 2.Collecting bag 47, of sufiiciently porous material todischarge the airand retain the dust. I have successfully cleaned a charge of erasers inthirty minutes with the machine I now have in operation, which machineembodies all the features set forth herein.

It will now be clear that I do not rely wholly upon suction or agitationalone, but on both. The agitation brings the dust to the surface, and ofcourse in so doing, actually releases some of it, and the suctioncarries ofi the released dust and also extracts the surface dust fromthe erasers. The speed of the fan is of course regulated so that suctionis not sufficient to drag the bouncing erasers toward or into the conedend of the drum as that would interfere with a free falling actioninitiated by the lifters. Hence, suction is only strong enough to drawout the dust ladened air.

It is believed that my improved machine will be fully understood fromthe foregoing description, and While I have herein shown and describedone specific form of the invention, I do not wish to be limited theretoexcept for such limitations as the claim may import.

I claim:

In an eraser cleaner, a rotatively driven drum having a cylindricalsection adapted to contain erasers sufiicient in number substantially toamount to congestion and provided with a conical section forming anextension of the interior of said cylindrical section and. said conicalsection having an outlet opening and the remaining end of saidcylindrical section having air intake openings, suction means connected.with said outlet opening for sustaining currents of air through saiddrum to carry of)? dust ladened air therefrom, said cylindrical sectionhaving lifters for lifting and then releasing the erasers to tumble thelatter whereby the tumbling erasers will continually obstruct and divertcurrents of dust ladened air from their normal courses, and a tubularabutment connected with said conical section and. discharging into saidoutlet opening and extending through said conical section and axiallythrough said cylindical section and. being secured thereto to rotatetherewith and form a revolving abutment to arrest and deflect erasersdescending thereagainst, said abutment being foraminous substantiallythroughout its length to form an elongated egress for entrance thereintoof obstructed currents of dust ladened air at any point lengthwise ofsaid drum.

CHARLES L. GILBERT.

